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Library Home Page > 2nd Generation (1999 to current) > Engine
Plugging the AIS
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Plugging the AIS

Taken from various posts in the discussion forum

The AIS is used to control HC and CO emissions. Air is injected into the exhaust system to allow post chamber combustion of the exhaust gases. On the Venture, the AIS injects fresh air into the exhaust ports whenever the intake vacuum is low, such as when cruising at steady throttle or accelerating. During high vacuum conditions, such as when decelerating, the vacuum is used to close a reed valve, thus shutting off the flow of air to the exhaust ports. This vacuum control is taken from the small pipes protruding from the intake manifolds on cylinders 1 and 3 (the 2 back ones). Disconnecting this system will eliminate the backfiring and popping experienced during deceleration by not allowing any air to be injected into the exhaust ports.

Since the air intake valve in the AIS system is normally open, simply removing the hose from the intake vacuum will cause it to be open all the time, making the popping worse. Thus you must close off the hoses going to the exhaust port. When this is done, no air can enter the exhaust ports.

Both hoses are accessible from the right side of the bike. You will need to lay on the ground to get the best access. Here's the best way to locate the rear AIS.
Look at the passengers floor board, divide it in half and go straight down and underneath the bike. You will see a silver type valve This is the reed valve. Attached to it is a 1 inch rubber hose. It is held in place with a finger type squeeze clamp. Don't disconnect it there. Follow the hose until you find the other clamp and disconnect it there. Now all you have to do is find something to plug the hole with. What I did was go to a place that sold laboratory supplies and bought one of the rubber stoppers that they put in test tubes. Works great. Other people have recommended pieces of sponge, 45 caliber cartridges, etc. But the rubber test tube stopper starts off with a samll diameter taper and gets bigger.
Now for the front AIS.
Find your oil filter. Look to the left of the oil filter and you will also see a 1 inch diameter hose. This is connected to a little black looking thing (looks like some sort of box) on the back of the shroud. It also has a finger type squeeze clamp on it. Disconnect it there and plug it with whatever you decide to use. As an alternative till I got my rubber stoppers, I looked around the garage and you know those little plastic caps they put on top of spray pump bottles? They fit up there nicely but was afraid they wouldn't last since they are hard brittle plastic.

The nice thing is to this day I have had not one single backfire. I have even revved it up real hard while driving and rolled off of the throttle real fast to try and induce a backfire and it hasn't happened.


Last update: 09:25 PM Friday, November 25, 2005

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